For example, an inverter in an air conditioner is formed into a power module in which necessary peripheral circuits are packaged, and this power module is attached to a printed wiring board. At that time, lead pins coming out of the power module are soldered to a copper pattern of the printed wiring board. Lead pins of a main circuit through which a current supplied to a motor flows are connected to a terminal block via the copper pattern on the board. A crimp terminal of the electric wire can be connected to the terminal block by screw clamp. The terminal block and other devices are disposed on, for example, a front surface of the printed wiring board, and the power module is disposed on a rear surface. The arrangement on the front and rear surfaces is convenient for attaching a radiation fin to the power module (for example, see Patent Literature 1 (FIG. 3)).